JP2013195338A - Uv index measuring apparatus and measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a portable UV index measuring apparatus capable of measuring a UV index with high accuracy, and a UV index measuring method.SOLUTION: The UV index measuring apparatus comprises: an optical filter transmitting light of a specific wavelength therethrough; an optical sensor including a wide-gap semiconductor, detecting light transmitting through the optical filter; and calculation means for obtaining a UV index on the basis of an output value of the optical sensor. The optical sensor has cut-off characteristics approximate to CIE action spectrum, and a relation of "λ>λ" is satisfied between a cut-off wavelength λof the optical sensor on a long-wavelength side and a cut-off wavelength λof the optical filter on a long-wavelength side.

Description

  The present invention relates to a portable UV index measuring apparatus and a UV index measuring method capable of measuring a UV index with high accuracy.

The UV index is known as an index that easily shows the degree of adverse effects of ultraviolet rays on the human body. UV index, A area ultraviolet rays reaching the earth (UV-A: Wavelength 315Nm～400nm) and B region ultraviolet: 250 nm the product of the intensity E _lambda and CIE action spectrum _{S er} of (UV-B wavelength 280Nm～315nm) It is obtained by integrating over ˜400 nm and dividing the obtained integrated value I _CIE by a constant.

また、強度Ｅ_λとＣＩＥ作用スペクトルＳ_ｅｒとの積は、例えば図２に示すスペクトルとなる。この図から明らかなように、ＵＶインデックスは、２９０ｎｍ〜３３０ｎｍの範囲の紫外線の強度Ｅ_λに強く依存する。 The CIE action spectrum _Ser is defined by the following equation, and this is shown in the graph as shown in FIG.

Further, the product of the intensity E _λ and the CIE action spectrum _Ser is, for example, the spectrum shown in FIG. As apparent from FIG, UV index is strongly dependent on the intensity E _lambda of the ultraviolet range of 290Nm～330nm.

As a conventional UV index measuring method, a method of measuring the intensity E _lambda of the UV-A and B regions ultraviolet with Brewer spectrophotometer they are known (e.g., see Non-Patent Document 1). According to this measurement method, the intensity E _λ for each wavelength can be measured with high accuracy, so that the UV index can be accurately measured by performing complicated digital processing such as integration. However, since the Brewer spectrophotometer is expensive and large, it is very difficult to carry it to any place for measurement or increase the number of installation places. For this reason, in order to obtain the UV index of the place where the Brewer spectrophotometer is not installed by this measurement method, there was nothing but to make an inaccurate analogy from the UV index measured at another place.

  In addition, as a conventional UV index measuring method, there is also known a method of detecting light of a specific wavelength transmitted through a filter with a semiconductor optical sensor and measuring the UV index based on the output value of the optical sensor. . In this measurement method, for example, a B region ultraviolet radiometer “MS-212W” manufactured by Eihiro Seiki is used. As shown in FIG. 3, the radiometer 10 includes an interference filter 11 that transmits light having a wavelength shorter than 350 nm, and a phosphor 12 that emits light having a wavelength different from that of the transmitted light by the transmitted light of the interference filter 11. A cut filter 13 that sharpens the emission spectrum of the phosphor 12 and a Si photodiode 14 (photosensor) that detects the light transmitted through the cut filter 13 are provided. In addition, the radiometer 10 also includes a quartz dome for collecting light and a diffusion plate for diffusing the collected light.

  The radiometer 10 is small enough to be carried and is not as expensive as a brewer spectrophotometer. Therefore, according to this measurement method, the UV index at an arbitrary place can be measured. However, in this measurement method, when the characteristics of the phosphor 12 or the cut filter 13 change due to changes over time and / or changes in the surrounding environment, the wavelength range and size of the light detected by the Si photodiode 14 are originally detected. There is a problem that the measurement accuracy deteriorates due to deviation from the desired wavelength range and size. Further, in this measurement method, since the Si photodiode 14 whose characteristics are easily changed is used, the output value changes despite the constant wavelength range and size of the detected light, and the measurement accuracy is improved. There was also the problem of getting worse.

  Furthermore, in this measurement method, it shows in FIG. 2 based on the result of having measured the light of the wavelength of the very narrow range selected by the filter (11, 13) of several steps, and the data regarding the atmospheric condition acquired separately. The UV index is obtained by a digital process of analogizing the spectrum and integrating the spectrum, but it is usually very difficult to accurately measure atmospheric conditions. This point was also a cause of error in this measurement method.

“To find UV index”, [online], Japan Meteorological Agency, March 13, 2012 search, Internet <URL: http://www.data.kishou.go.jp/obs-env/uvhp/3- 41uvindex_define.html>

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a portable UV index measuring apparatus and a UV index measuring method capable of accurately measuring a UV index. is there.

  In order to solve the above-mentioned problems, the present inventor has made extensive studies, and as a result, uses an optical sensor having a cutoff characteristic approximated to a CIE action spectrum, and transmits light having a wavelength necessary for UV index measurement. As a result of the analog integration, the present inventors have found that the same results as those obtained when the complex digital processing is performed using a Brewer spectrophotometer can be easily obtained, and the present invention has been completed.

That is, the UV index measuring device according to the present invention includes an optical filter that transmits light of a specific wavelength, an optical sensor that includes a wide gap semiconductor that detects transmitted light of the optical filter, and an UV index based on an output value of the optical sensor. The optical sensor has a cutoff characteristic that approximates the CIE action spectrum, and the cutoff wavelength λ _s on the long wavelength side of the optical sensor and the cutoff wavelength λ _f on the long wavelength side of the optical filter There is a relationship of “λ _f > λ _s ” between them.

  In this configuration, the optical sensor itself has a cutoff characteristic that approximates the CIE action spectrum. Further, in this configuration, an optical filter is supplementarily provided to shield long wavelength light that has only a minute influence on the measurement result. Therefore, in this configuration, even if the characteristics of the optical filter change due to changes over time and / or changes in the surrounding environment, the output value of the optical sensor hardly varies. That is, according to this configuration, the UV index can always be measured with high accuracy.

  In addition, according to this configuration, since the main components are only the optical filter, the optical sensor, and the calculation means, a small and lightweight UV index measuring device can be realized.

In the UV index measuring apparatus, it is preferable that a relationship of “λ _f −λ _s ≧ 20 nm” _exists between the cutoff wavelength λ _s of the optical sensor and the cutoff wavelength λ _f of the optical filter. More specifically, in the UV index measuring device, the cutoff wavelength λ _s of the optical sensor is set within the range of 290 nm to 310 nm, and the cutoff wavelength λ _f of the optical filter is within the range of 320 nm to 400 nm. It is preferable that it is set.

  According to this configuration, since the buffer zone having a width of 20 nm is provided, it is possible to reliably prevent deterioration in measurement accuracy due to changes in the characteristics of the optical filter.

In the UV index measuring apparatus, the optical sensor is Al _x Ga _y In _1-xy N (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1-x) or Zn _x Mg _1-x O (where 0 It is preferable that the ultraviolet sensor is composed of ≦ x ≦ 1).

  According to this configuration, the cutoff characteristic can be easily approximated to the CIE action spectrum by adjusting the composition ratio of Al, Ga, and In or the composition ratio of Zn and Mg.

  In the UV index measuring apparatus, the optical filter is preferably a colored glass filter.

  Color glass filters are easily available and inexpensive. Therefore, according to this configuration, the manufacturing cost of the UV index measuring device can be reduced.

In order to solve the above-mentioned problem, the UV index measurement method according to the present invention uses the transmitted light of the optical filter in which the cut-off wavelength λ _f on the long wavelength side is set within the range of 320 nm to 400 nm, Detecting with an optical sensor made of a wide-gap semiconductor whose cutoff wavelength λ _s is set within a range of 290 nm to 310 nm, and obtaining a UV index based on the output value of the optical sensor. Features.

As in the case of the UV index measuring device, in the above UV index measuring method, the optical sensor is Al _x Ga _y In _1-xy N (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1-x) or Zn _An ultraviolet sensor made of xMg1 _-xO (where 0 ≦ x ≦ 1) is preferable. The optical filter is preferably a colored glass filter.

  ADVANTAGE OF THE INVENTION According to this invention, the portable UV index measuring apparatus and UV index measuring method which can measure a UV index accurately can be provided.

It is a graph which shows CIE action spectrum _Ser . It is a graph which shows an example of the product of intensity _| strength E ( _lambda ) of the ultraviolet-ray which reached | attained on the ground, and CIE action spectrum _Ser . It is a figure which shows the measurement principle of the conventional ultraviolet radiometer. It is a disassembled schematic diagram of the UV index measuring device according to an embodiment of the present invention. It is a graph regarding the UV index measuring apparatus which concerns on one Embodiment of this invention, Comprising: (A) is a graph which shows the sensitivity characteristic of an optical sensor, (B) is a graph which shows the permeation | transmission characteristic of an optical filter, (C) is an optical sensor It is a graph which shows the sensitivity characteristic of the UV index measuring device which combines an optical filter. It is a graph which shows an example of the rule used with the UV index measuring device concerning one embodiment of the present invention.

  Hereinafter, embodiments of a UV index measuring device and a UV index measuring method according to the present invention will be described with reference to the accompanying drawings.

  FIG. 4 is a diagram showing only main components of the UV index measuring apparatus according to an embodiment of the present invention. As shown in the figure, the UV index measuring apparatus 1 according to the present embodiment includes a quartz dome 2, a diffusion plate 3, an optical filter 4, an optical sensor 5, and a circuit board 6. Although not shown, the UV index measuring device 1 includes a light shielding exterior member that covers the diffusion plate 3, the optical filter 4, the optical sensor 5, and the circuit board 6, and a power source that supplies power to the optical sensor 5 and the circuit board 6. (For example, a rechargeable battery or a button battery). The UV index measurement apparatus 1 may further include a means for displaying the measured UV index and a communication means for transmitting data relating to the measured UV index to another device.

  The quartz dome 2 collects ambient light and takes it into the UV index measuring device 1, and is provided at the window portion of the UV index measuring device 1. The quartz dome 2 also serves to prevent rainwater and the like from entering the UV index measuring device 1. The diffusion plate 3 diffuses the light taken in by the quartz dome 2. Thereby, uniform light is irradiated to the optical filter 4.

  As the quartz dome 2 and the diffusing plate 3, those used in the conventional radiometer 10 or the like can be used. Note that the quartz dome 2 and the diffusion plate 3 can be omitted when used in an environment where it is not necessary to collect or diffuse light.

The optical filter 4 transmits light of a specific wavelength among the diffused light from the diffusion plate 3. In the present embodiment, a color glass filter having transmission characteristics as shown in FIG. 5B is used as the optical filter 4. As shown in the figure, the optical filter 4 has a cut-off wavelength on the long wavelength side, that is, a wavelength λ _{f at} which the transmittance is 1 / √2 of the maximum value is about 365 nm, and has a wavelength longer than the wavelength. (But not completely shielded).

  In the present embodiment, the colored glass filter is used because it is easily available and inexpensive. However, any low-pass filter that can shield light having a long wavelength may be used as the optical filter 4. .

The optical sensor 5 detects the intensity of light having a specific wavelength that has passed through the optical filter 4 and outputs an electrical signal corresponding to the intensity. In the present embodiment, Al _x Ga _y In _1-xy N (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1-x) whose characteristics are unlikely to change even when used for a long time in an environment exposed to ultraviolet rays. ) Is used as the optical sensor 5. Figure 5 (A), the optical sensor 5, the long wavelength side of the cut-off wavelength, i.e. the wavelength lambda _s of about 305nm as a 1 / √2 of the sensitivity is the maximum value, the shorter than the wavelength High sensitivity to wavelength light. The optical sensor 5 has a sensitivity of about 1/1000 of the maximum sensitivity even for light having a wavelength longer than the cutoff wavelength λ _s .

As the optical sensor 5, another ultraviolet sensor made of a wide gap semiconductor can be used. For example, an ultraviolet sensor made of Zn _x Mg _1-x O (where 0 ≦ x ≦ 1) can also be used. .

  As a result of adjusting the composition ratio xy, the optical sensor 5 according to the present embodiment has a cut-off characteristic that the sensitivity rapidly decreases from 300 nm to 320 nm. This characteristic is very similar to the CIE action spectrum shown in FIG.

  In the UV index measuring apparatus 1 according to this embodiment, the optical sensor 5 having the sensitivity characteristic shown in FIG. 5A detects the intensity of the transmitted light of the optical filter 4 having the transmission characteristic shown in FIG. Therefore, the sensitivity characteristic when viewed as a whole of the UV index measuring apparatus 1 is obtained by multiplying the sensitivity characteristic of the optical sensor 5 and the transmission characteristic of the optical filter 4.

  The sensitivity characteristic of the UV index measuring device 1 is indicated by a thick solid line in FIG. As shown in the figure, the sensitivity of the UV index measuring apparatus 1 changes abruptly at 300 nm to 320 nm and 370 nm to 400 nm. The change at 300 nm to 320 nm is due to the sensitivity characteristic of the optical sensor 5. Further, the change at 370 nm to 400 nm is due to the transmission characteristics of the optical filter 4.

  The circuit board 6 is equipped with arithmetic means for obtaining a UV index based on the output value of the optical sensor 5. In this embodiment, the calculation means includes an I / V converter that converts the output current of the optical sensor 5 into a voltage, and a replacement unit that replaces the voltage obtained by the conversion with a UV index based on a predetermined rule. It is configured. In the present embodiment, the relationship shown in FIG. 6 is used as a rule used for replacement. According to this rule, the voltage obtained by the I / V conversion can be replaced with the UV index.

  The obtained UV index is stored together with the measurement time in a storage unit provided in the UV index measuring apparatus 1 or displayed on a small display provided in the UV index measuring apparatus 1. The obtained data relating to the UV index may be sent to another device that can communicate with the UV index measuring apparatus 1.

  Various modifications can be considered for the rules used when determining the configuration of the calculation means and the UV index. In the present invention, any calculation means and rule that can obtain the UV index based on the output value of the optical sensor 5 can be used.

As described above, in the UV index measuring apparatus 1 according to the present embodiment, the sensitivity characteristic indicated by the thick solid line in FIG. 5C is obtained by multiplying the sensitivity characteristic of the optical sensor 5 and the transmission characteristic of the optical filter 4. Is realized. This sensitivity characteristic approximates the CIE action spectrum indicated by a broken line in FIG. Therefore, according to the UV index measuring apparatus 1 according to this embodiment, correlated to the integral value _{I CIE} (value obtained by integrating over 250nm~400nm the product of the intensity E _lambda and CIE action spectrum _{S er} UV) An output value is obtained from the optical sensor 5.

Further, in the UV index measuring apparatus 1 according to the present embodiment, since an optical filter that shields long wavelength light is supplementarily provided, the output value of the optical sensor 5 has a long wavelength that is unrelated to the measurement of the UV index. Can be prevented from being affected by light. Here, since the cutoff wavelength λ _f of the optical filter 4 is set to a wavelength at which the intensity E _{λ of} the ultraviolet light is considerably attenuated, even if the cutoff wavelength λ _f varies, the output value of the optical sensor 5 Almost no effect. Therefore, according to the UV index measuring apparatus 1 according to the present embodiment, the UV index can always be measured with high accuracy. Note that the amount of fluctuation of the cutoff wavelength λ _s of the optical sensor 5 made of a wide gap semiconductor is so small that it does not need to be considered.

In order to obtain the above effect, it is preferable to set the cutoff wavelength λ _s of the optical sensor 5 within a range of 290 nm to 310 nm. If the cutoff wavelength λ _s is out of this range, the correlation between the output value of the optical sensor 5 and the integrated value I _CIE is lost, and the measurement accuracy of the UV index may be deteriorated.

Further, in order to obtain the above-described effect, it is essential that the relationship between the cutoff wavelength λ _f of the optical filter 4 and the cutoff wavelength λ _s of the optical sensor 5 is “λ _f > λ _s ”. In order to surely eliminate the influence of fluctuations in the cutoff wavelength λ _f , it is preferable to satisfy “λ _f −λ _s ≧ 20 nm”. Further, from the viewpoint of preventing the output value of the optical sensor 5 from being affected by light having a long wavelength unrelated to the measurement of the UV index, the cutoff wavelength λ _f of the optical filter 4 is 400 nm or less. Is preferred.

In summary, in the present invention, the cutoff wavelength λ _s of the optical sensor 5 is set within the range of 290 nm to 310 nm, and the cutoff wavelength λ _f of the optical filter 4 is set within the range of 330 nm to 400 nm. It is preferable to do.

DESCRIPTION OF SYMBOLS 1 UV index measuring device 2 Quartz dome 3 Diffusing plate 4 Optical filter 5 Optical sensor 6 Circuit board

Claims (8)

An optical filter that transmits light of a specific wavelength; an optical sensor made of a wide-gap semiconductor that detects the transmitted light of the optical filter; and an arithmetic unit that obtains a UV index based on an output value of the optical sensor,
The optical sensor has a cut-off characteristic approximating a CIE action spectrum,
The UV index characterized in that there is a relationship of “λ _f > λ _s ” between the cut-off wavelength λ _s on the long wavelength side of the optical sensor and the cut-off wavelength λ _f on the long wavelength side of the optical filter. measuring device. 2. The UV index according to claim 1, wherein a relationship of “λ _f −λ _s ≧ 20 nm” _exists between the cutoff wavelength λ _s of the optical sensor and the cutoff wavelength λ _f of the optical filter. measuring device. The cut-off wavelength λ _s of the optical sensor is set within a range of 290 nm to 310 nm, and the cut-off wavelength λ _f of the optical filter is set within a range of 320 nm to 400 nm. 2. The UV index measuring device according to 1. The optical sensor is Al _x Ga _y In _1-xy N (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1-x), or Zn _x Mg _1-x O (where 0 ≦ x ≦ 1). The UV index measuring device according to claim 1, wherein the UV index measuring device is an ultraviolet sensor.   The UV index measuring device according to claim 1, wherein the optical filter is a colored glass filter. Wide-gap semiconductor with long wavelength cutoff wavelength λ _s set within the range of 290 nm to 310 nm is transmitted through the optical filter with the long wavelength side cutoff wavelength λ _f set within the range of 320 nm to 400 nm. Detecting with an optical sensor comprising:
Obtaining a UV index based on the output value of the photosensor;
A UV index measurement method comprising: The optical sensor is Al _x Ga _y In _1-xy N (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1-x), or Zn _x Mg _1-x O (where 0 ≦ x ≦ 1). The UV index measuring method according to claim 6, wherein the UV index measuring method is an ultraviolet sensor.   The UV index measuring method according to claim 6, wherein the optical filter is a colored glass filter.

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